Geospatial information services composition is a promising approach to construct complex Web GIS applications. BPEL, which is the language and the industry standard that expresses complex concurrent business processes for web services composition, is efficient at composing the geospatial information services chain. This paper concludes the BPEL control flows to four basic models which can be applied to orchestrate the geospatial information services, and realizes the data reduction process service based on BPEL in a watershed management system. Keywords-Geospatial Information Service, Service chain, BPEL